/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.apache.iotdb.db.protocol.rest.handler;

import org.apache.iotdb.commons.exception.IoTDBException;
import org.apache.iotdb.db.mpp.common.header.DatasetHeader;
import org.apache.iotdb.db.mpp.plan.execution.IQueryExecution;
import org.apache.iotdb.db.mpp.plan.statement.Statement;
import org.apache.iotdb.db.mpp.plan.statement.crud.QueryStatement;
import org.apache.iotdb.db.mpp.plan.statement.metadata.ShowChildPathsStatement;
import org.apache.iotdb.db.mpp.plan.statement.metadata.ShowStatement;
import org.apache.iotdb.db.mpp.plan.statement.sys.AuthorStatement;
import org.apache.iotdb.db.protocol.rest.model.ExecutionStatus;
import org.apache.iotdb.rpc.TSStatusCode;
import org.apache.iotdb.tsfile.file.metadata.enums.TSDataType;
import org.apache.iotdb.tsfile.read.common.Path;
import org.apache.iotdb.tsfile.read.common.block.TsBlock;
import org.apache.iotdb.tsfile.read.common.block.column.Column;
import org.apache.iotdb.tsfile.read.query.dataset.QueryDataSet;

import javax.ws.rs.core.Response;
import java.util.ArrayList;
import java.util.List;
import java.util.Map;
import java.util.Optional;

public class QueryDataSetHandler {

    private QueryDataSetHandler() {
    }

    /**
     * @param actualRowSizeLimit max number of rows to return. no limit when actualRowSizeLimit <= 0.
     */
    public static Response fillQueryDataSet(
            IQueryExecution queryExecution, Statement statement, int actualRowSizeLimit)
            throws IoTDBException {
        if (statement instanceof ShowStatement || statement instanceof AuthorStatement) {
            return fillShowPlanDataSet(queryExecution, actualRowSizeLimit);
        } else if (statement instanceof QueryStatement) {
            if (((QueryStatement) statement).isAggregationQuery()
                    && !((QueryStatement) statement).isGroupByTime()) {
                return fillAggregationPlanDataSet(queryExecution, actualRowSizeLimit);
            }
            return fillDataSetWithTimestamps(queryExecution, actualRowSizeLimit, 1);
        }
        return Response.ok()
                .entity(
                        new ExecutionStatus()
                                .code(TSStatusCode.QUERY_PROCESS_ERROR.getStatusCode())
                                .message(
                                        String.format(
                                                "unsupported query data type: %s", statement.getType().toString())))
                .build();
    }

    public static Response fillDataSetWithTimestamps(
            IQueryExecution queryExecution, final int actualRowSizeLimit, final long timePrecision)
            throws IoTDBException {
        org.apache.iotdb.db.protocol.rest.model.QueryDataSet targetDataSet =
                new org.apache.iotdb.db.protocol.rest.model.QueryDataSet();

        return fillQueryDataSetWithTimestamps(
                queryExecution, actualRowSizeLimit, targetDataSet, timePrecision);
    }

    public static Response fillAggregationPlanDataSet(
            IQueryExecution queryExecution, final int actualRowSizeLimit) throws IoTDBException {

        org.apache.iotdb.db.protocol.rest.model.QueryDataSet targetDataSet =
                new org.apache.iotdb.db.protocol.rest.model.QueryDataSet();

        DatasetHeader datasetHeader = queryExecution.getDatasetHeader();

        for (int i = 0; i < datasetHeader.getRespColumns().size(); i++) {
            targetDataSet.addExpressionsItem(datasetHeader.getRespColumns().get(i));
            targetDataSet.addValuesItem(new ArrayList<>());
        }

        return fillQueryDataSetWithoutTimestamps(queryExecution, actualRowSizeLimit, targetDataSet);
    }

    private static Response fillShowPlanDataSet(
            IQueryExecution queryExecution, final int actualRowSizeLimit) throws IoTDBException {
        org.apache.iotdb.db.protocol.rest.model.QueryDataSet targetDataSet =
                new org.apache.iotdb.db.protocol.rest.model.QueryDataSet();
        initTargetDatasetOrderByOrderWithSourceDataSet(
                queryExecution.getDatasetHeader(), targetDataSet);

        return fillQueryDataSetWithoutTimestamps(queryExecution, actualRowSizeLimit, targetDataSet);
    }

    private static void initTargetDatasetOrderByOrderWithSourceDataSet(
            DatasetHeader datasetHeader,
            org.apache.iotdb.db.protocol.rest.model.QueryDataSet targetDataSet) {
        if (datasetHeader.getRespColumns() != null) {
            for (int i = 0; i < datasetHeader.getRespColumns().size(); i++) {
                targetDataSet.addColumnNamesItem(datasetHeader.getRespColumns().get(i));
                targetDataSet.addValuesItem(new ArrayList<>());
            }
        }
    }

    private static void initTargetDatasetExpByOrderWithSourceDataSet(
            QueryDataSet sourceDataSet,
            int[] targetDataSetIndexToSourceDataSetIndex,
            org.apache.iotdb.db.protocol.rest.model.QueryDataSet targetDataSet) {
        if (sourceDataSet.getPaths() != null) {
            for (int i = 0; i < sourceDataSet.getPaths().size(); i++) {
                Path path = sourceDataSet.getPaths().get(i);
                targetDataSet.addExpressionsItem(path.getFullPath());
                targetDataSet.addValuesItem(new ArrayList<>());
                targetDataSetIndexToSourceDataSetIndex[i] = i;
            }
        }
    }

    private static Response fillQueryDataSetWithTimestamps(
            IQueryExecution queryExecution,
            int actualRowSizeLimit,
            org.apache.iotdb.db.protocol.rest.model.QueryDataSet targetDataSet,
            final long timePrecision)
            throws IoTDBException {
        int fetched = 0;
        int columnNum = queryExecution.getOutputValueColumnCount();

        DatasetHeader header = queryExecution.getDatasetHeader();
        List<String> resultColumns = header.getRespColumns();
        Map<String, Integer> headerMap = header.getColumnNameIndexMap();
        for (String resultColumn : resultColumns) {
            targetDataSet.addExpressionsItem(resultColumn);
            targetDataSet.addValuesItem(new ArrayList<>());
        }

        while (true) {
            if (0 < actualRowSizeLimit && actualRowSizeLimit <= fetched) {
                return Response.ok()
                        .entity(
                                new org.apache.iotdb.db.protocol.rest.model.ExecutionStatus()
                                        .code(TSStatusCode.QUERY_PROCESS_ERROR.getStatusCode())
                                        .message(
                                                String.format(
                                                        "Dataset row size exceeded the given max row size (%d)",
                                                        actualRowSizeLimit)))
                        .build();
            }
            Optional<TsBlock> optionalTsBlock = queryExecution.getBatchResult();
            if (!optionalTsBlock.isPresent()) {
                if (fetched == 0) {
                    targetDataSet.setTimestamps(new ArrayList<>());
                    targetDataSet.setValues(new ArrayList<>());
                    return Response.ok().entity(targetDataSet).build();
                }
                break;
            }
            TsBlock tsBlock = optionalTsBlock.get();
            int currentCount = tsBlock.getPositionCount();
            // time column
            for (int i = 0; i < currentCount; i++) {
                targetDataSet.addTimestampsItem(
                        timePrecision == 1
                                ? tsBlock.getTimeByIndex(i)
                                : tsBlock.getTimeByIndex(i) / timePrecision);
            }
            for (int k = 0; k < resultColumns.size(); k++) {
                Column column = tsBlock.getColumn(headerMap.get(resultColumns.get(k)));
                List<Object> targetDataSetColumn = targetDataSet.getValues().get(k);
                for (int i = 0; i < currentCount; i++) {
                    fetched++;
                    if (column.isNull(i)) {
                        targetDataSetColumn.add(null);
                    } else {
                        targetDataSetColumn.add(
                                column.getDataType().equals(TSDataType.TEXT)
                                        ? column.getBinary(i).getStringValue()
                                        : column.getObject(i));
                    }
                }
                if (k != columnNum - 1) {
                    fetched -= currentCount;
                }
            }
        }
        return Response.ok().entity(targetDataSet).build();
    }

    private static Response fillQueryDataSetWithoutTimestamps(
            IQueryExecution queryExecution,
            int actualRowSizeLimit,
            org.apache.iotdb.db.protocol.rest.model.QueryDataSet targetDataSet)
            throws IoTDBException {
        int fetched = 0;
        int columnNum = queryExecution.getOutputValueColumnCount();
        while (true) {
            if (0 < actualRowSizeLimit && actualRowSizeLimit <= fetched) {
                return Response.ok()
                        .entity(
                                new org.apache.iotdb.db.protocol.rest.model.ExecutionStatus()
                                        .code(TSStatusCode.QUERY_PROCESS_ERROR.getStatusCode())
                                        .message(
                                                String.format(
                                                        "Dataset row size exceeded the given max row size (%d)",
                                                        actualRowSizeLimit)))
                        .build();
            }
            Optional<TsBlock> optionalTsBlock = queryExecution.getBatchResult();
            if (!optionalTsBlock.isPresent()) {
                if (fetched == 0) {
                    targetDataSet.setValues(new ArrayList<>());
                    return Response.ok().entity(targetDataSet).build();
                }
                break;
            }
            TsBlock tsBlock = optionalTsBlock.get();
            int currentCount = tsBlock.getPositionCount();
            if (currentCount == 0) {
                targetDataSet.setValues(new ArrayList<>());
                return Response.ok().entity(targetDataSet).build();
            }
            for (int k = 0; k < columnNum; k++) {
                Column column = tsBlock.getColumn(k);
                List<Object> targetDataSetColumn = targetDataSet.getValues().get(k);
                for (int i = 0; i < currentCount; i++) {
                    fetched++;
                    if (column.isNull(i)) {
                        targetDataSetColumn.add(null);
                    } else {
                        targetDataSetColumn.add(
                                column.getDataType().equals(TSDataType.TEXT)
                                        ? column.getBinary(i).getStringValue()
                                        : column.getObject(i));
                    }
                }
                if (k != columnNum - 1) {
                    fetched -= currentCount;
                }
            }
        }
        return Response.ok().entity(targetDataSet).build();
    }

    public static Response fillGrafanaVariablesResult(
            IQueryExecution queryExecution, Statement statement) throws IoTDBException {
        List<String> results = new ArrayList<>();
        Optional<TsBlock> optionalTsBlock = queryExecution.getBatchResult();
        if (!optionalTsBlock.isPresent()) {
            return Response.ok().entity(results).build();
        }
        TsBlock tsBlock = optionalTsBlock.get();
        int currentCount = tsBlock.getPositionCount();
        Column column = tsBlock.getColumn(0);

        for (int i = 0; i < currentCount; i++) {
            String nodePaths = column.getObject(i).toString();
            if (statement instanceof ShowChildPathsStatement) {
                String[] nodeSubPath = nodePaths.split("\\.");
                results.add(nodeSubPath[nodeSubPath.length - 1]);
            } else {
                results.add(nodePaths);
            }
        }
        return Response.ok().entity(results).build();
    }

    public static Response fillGrafanaNodesResult(IQueryExecution queryExecution)
            throws IoTDBException {
        List<String> nodes = new ArrayList<>();
        Optional<TsBlock> optionalTsBlock = queryExecution.getBatchResult();
        if (!optionalTsBlock.isPresent()) {
            return Response.ok().entity(nodes).build();
        }
        TsBlock tsBlock = optionalTsBlock.get();
        int currentCount = tsBlock.getPositionCount();
        Column column = tsBlock.getColumn(0);

        for (int i = 0; i < currentCount; i++) {
            String nodePaths = column.getObject(i).toString();
            String[] nodeSubPath = nodePaths.split("\\.");
            nodes.add(nodeSubPath[nodeSubPath.length - 1]);
        }
        return Response.ok().entity(nodes).build();
    }
}
